Conventionally, in cases where aesthetics resembling a natural tooth are desired in dental prostheses such as crowns and bridges, resin-faced cast crowns, porcelain-baked-faced cast crowns, resin-faced bridges, porcelain-baked bridges, all-ceramic crowns, and the like may be used, for example. Methods for producing such dental prostheses involve making an impression (counterdie of tooth) from the oral cavity of a patient subjected to formation of an abutment tooth, creating a model (replica of tooth) from the impression using resin or plaster, for example, and fabricating the dental prosthesis based on this model using the lost wax technique, for example. The lost wax technique involves, first preparing a wax pattern of a core portion by applying wax in an abutment tooth die, embedding the wax pattern with a refractory investment material, and after the investment material is hardened, placing the investment material in an electric furnace to burn out the wax pattern. Then, metal is cast into the resulting mold, and after retrieving the cast metal from the investment material, the cast metal is cut and polished to fabricate a metal prosthesis. Alternatively, a dental prosthesis may be fabricated by preparing a metal coping, and thereafter building up and polymerizing hard resin for a crown on the resulting metal coping portion, for example. In the case of fabricating an all-ceramic crown, a composite model is prepared using a refractory die material, and after building up and firing a porcelain material in the composite model, the porcelain material is removed from the composite model and is finished and polished.
Normally, the above procedures are performed by a dental technician, and it generally takes about 3 days to a week before the final prosthesis can be inserted into the mouth of the patient. Meanwhile, in cases where an abutment tooth formed by a dentist is needed, a temporary prosthesis is formed by a dentist, and such a temporary prosthesis is temporarily inserted until the final prosthesis can be inserted. Such a temporary prosthesis is inserted in order to prevent the abutment tooth from being exposed to physical impacts such as food hitting the abutment tooth during a meal, chemical impacts such as exposure to acid, and stimulation from the temperature of food, for example. A temporary prosthesis has other important functions such as maintaining the occlusal function and restoring aesthetics of the teeth, for example.
Conventional temporary prostheses are mainly fabricated using a room temperature polymerization resin (also referred to as “immediate polymerization resin”) or a dedicated two-liquid mixture paste resin (see e.g. Patent Documents 1 and 2). The room temperature polymerization resin may be prepared by mixing a (meth)acrylic acid ester polymer powder and a (meth)acrylic acid ester monomer powder solution, for example, and the temporary prosthesis may be fabricated using a mold prepared in advance using the above mixture, for example. Alternatively, the temporary prosthesis may be fabricated directly in the oral cavity of the patient or on a model using the so-called brush-on technique, for example (see e.g. Patent Documents 3 and 4).
However, in general, temporary prostheses fabricated using room temperature polymerization resin or conventional paste resin contain filler at a relatively small ratio and therefore tend to wear easily and have relatively low strength. As such, temporary prostheses have been prone to wear due to occlusion pressure, for example, and cause occlusal problems even when they are used only for a short period of about several days to a week, for example. Also, depending on circumstances such as the schedule of the patient, there may be cases where temporary prostheses are used for up to a few months, and the above problems due to wear become even more conspicuous in such cases. Further, regardless of the use period, conventional temporary prostheses are susceptible to damage or breakage that may be caused by the consumption of tough solid food, for example, and as such, there is a demand for a temporary prosthesis having greater strength.
In recent years, prosthesis fabrication using CAD/CAM technology is becoming widespread, and by using such technology to fabricate a temporary prosthesis, the strength of the temporary prosthesis may be increased (see e.g. Patent Documents 5 and 6). However fabrication procedures using CAD/CAM tend to be more complicated compared to fabrication using room temperature polymerization resin, which can be prepared on site, and the time required for fabrication using CAD/CAM is not much different from fabrication using the lost wax technique.